1. Field of the Invention
Aspects of the present invention relate to a technology to input a user command on a touch screen, and more particularly, to a display device and method of sensing an input point using magnetic fluid that causes a user to feel a touch using magnetic fluid when a user input is made on a touch screen.
2. Description of the Related Art
Generally, haptic technology is divided into force feedback, tactile feedback, and thermal feedback. Specifically, force feedback is a technology using kinesthetic information, tactile feedback is a technology using tactile information, and thermal feedback is a technology using thermal information. Conventional technologies generally provide vibrations to a user based on kinesthetic information, and are disclosed in various patent documents (e.g., U.S. Pat. No. 6,278,439, which discloses a method and apparatus to transfer vibrations based on force feedback).
Among them, the force feedback technology using the kinesthetic information is a technology capable of causing a user to feel force and motion using a mechanical interface, and can be easily experienced in daily life. For example, if a gun is fired in a game machine, a repulsion force is actually transferred to a joystick, or if a car collision occurs, a virtual impact is transferred to a steering wheel.
The tactile feedback using tactile information has been widely used in the medical field. For example, a three dimensional (3D) image is displayed in real time on a computer screen, and a user can directly operate an affected part with respect to a virtual patient as the user is looking at a 3D anatomical structure on the computer screen. In this case, the touch, as if the user actually touched skin tissue, is transferred to the user by stimulating a human mechanoreceptor through a device (such as a small pin) that is moved by compressed air or electricity.
Many documents related to the prior art as described above have been disclosed. Korean Patent Unexamined Publication No. 2003-082968 discloses a haptic interface for a laptop computer and other portable devices in which an actuator moves a touch pad surface itself so that a user can immediately sense such movement through his/her skin, and another control region is provided to provide a separate input. Also, Korean Patent Unexamined Publication No. 2002-064603 discloses a human body reaction type touch screen that is provided with screen electrodes that sense a user manipulation by a feedback current flowing to a touch screen, and leads stimulations through the sense of vision, the sense of hearing, and the sense of touch.
FIG. 1 is a view illustrating a structure of a general touch screen according to the prior art. Referring to FIG. 1, the general touch screen includes a plastic film 11, a first electrode 12, a gap 13, a second electrode 14, and an image display part 15. If a user applies pressure onto the plastic film 11 using a finger or a tool (such as a pen or the like), the first electrode 12 and the second electrode 14, which have the gap 13 interposed therebetween, contact each other to generate an electric signal. Such an electric signal is sensed by the image display part 15, and a calculated coordinate value on a screen is used as an input value. In response to such an input value, a screen change or sound is generated as a feedback. According to the conventional touch panel as described above, however, if the screen change or the sound is not generated, it is difficult for the user to recognize whether the signal inputted by the user has been accurately inputted through the touch panel.